Question

1. a balloon is blown up so that it is half way filled. use complete sentences to receive full credit.

a. if the person places the balloon over a fire, what will happen to the volume and pressure of the air inside the balloon?
b. if the person places the balloon inside the freezer, what will happen to the volume and pressure of the air inside the balloon?

1. a glass jar is filled $\frac{3}{4}$ of the way with a very hot fruit preserve and the lid is immediately closed. the jar is placed in the refrigerator where it cools down. what happens to the pressure and volume of the air inside the jar as it cools? use complete sentences to receive full credit.

Explanation:

For 7a:

This relies on Charles's Law (for volume) and Gay-Lussac's Law (for pressure, as the balloon can expand to keep internal pressure equal to atmospheric initially, then pressure stabilizes). When heated over a fire, the air temperature rises. The flexible balloon allows volume to increase first to maintain pressure equal to outside atmospheric pressure; as heating continues, the volume will expand significantly until the balloon reaches its maximum stretch, after which pressure would rise, but since it's only halfway filled initially, the primary change is volume increasing, with pressure remaining equal to atmospheric until the balloon is fully expanded.

For 7b:

Using Charles's Law and gas behavior in a flexible container. When cooled in a freezer, the air temperature drops. The flexible balloon contracts, so the volume of the air inside decreases, and the pressure stays equal to the outside atmospheric pressure as the balloon adjusts to the lower temperature.

For 8:

This uses Gay-Lussac's Law (since the jar is rigid, volume is fixed). The air in the jar is trapped in a fixed volume. As the jar cools, the temperature of the air drops, so the pressure of the air inside the jar decreases, while the volume of the air remains constant because the rigid jar cannot change shape.

Answer:

7a. When the balloon is placed over a fire, the temperature of the air inside increases. The flexible balloon will expand, so the volume of the air inside will increase, and the pressure of the air will stay equal to the outside atmospheric pressure until the balloon reaches its maximum capacity.
7b. When the balloon is placed inside the freezer, the temperature of the air inside decreases. The flexible balloon will shrink, so the volume of the air inside will decrease, and the pressure of the air will remain equal to the outside atmospheric pressure as the balloon contracts.

1. As the jar cools in the refrigerator, the volume of the air inside the rigid jar stays constant, and the pressure of the air inside the jar will decrease because the cooling reduces the kinetic energy of the air molecules, lowering the force they exert on the jar's walls.